/* ============================================================
   RESET & VARIABLES
   ============================================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --secondary-color: #8b5cf6;
    --accent-color: #ec4899;
    --light-bg: #f8fafc;
    --darker-bg: #1e293b;
    --text-dark: #1e293b;
    --text-light: #64748b;
    --border-color: #e2e8f0;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --space-blue: #0f172a;
    --cosmic-purple: #7c3aed;
    --nebula-pink: #f472b6;
}

/* ============================================================
   BASE
   ============================================================ */
body {
    font-family: "Inter", "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #0f172a 0%, #1e1b4b 50%, #312e81 100%);
    background-attachment: fixed;
    color: var(--text-dark);
    line-height: 1.6;
    scroll-behavior: smooth;
    overflow-x: hidden;
}

/* ============================================================
   HEADER & NAVBAR  (desktop)
   ============================================================ */
header {
    background: rgba(15, 23, 42, 0.95);
    backdrop-filter: blur(20px);
    padding: 1.2rem 0;
    box-shadow: 0 4px 30px rgba(99, 102, 241, 0.3);
    position: sticky;
    top: 0;
    z-index: 999;
    animation: slideDown 0.5s ease-out;
    border-bottom: 1px solid rgba(99, 102, 241, 0.2);
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.navbar {
    display: flex;
    align-items: center;
    padding: 0 2rem;
    max-width: 1400px;
    margin: auto;
    justify-content: space-between;
}

.navbar-logo-group {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    margin-right: 2rem;
    flex-shrink: 0;
}

.iit-logo {
    height: 45px;
    transition: transform 0.3s ease;
}
.iit-logo:hover {
    transform: scale(1.05);
}

.logo {
    height: 60px;
    transition: transform 0.3s ease;
}
.logo:hover {
    transform: scale(1.05);
}

/* nav-menu wraps both <ul> and the registration btn */
.nav-menu {
    display: flex;
    align-items: center;
    flex: 1;
    justify-content: space-between;
}

.navlinks {
    list-style: none;
    display: flex;
    gap: 2rem;
    flex: 1;
}

.navlinks a {
    text-decoration: none;
    color: #fff;
    font-weight: 500;
    font-size: 0.95rem;
    position: relative;
    transition: all 0.3s ease;
    padding: 0.5rem 0;
}

.navlinks a::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 2px;
    background: linear-gradient(
        90deg,
        var(--primary-color),
        var(--secondary-color)
    );
    transition: width 0.3s ease;
}
.navlinks a:hover::after {
    width: 100%;
}
.navlinks a:hover {
    color: #a5b4fc;
    transform: translateY(-2px);
}

/* hide the chevron arrows on desktop */
.dropdown-arrow {
    display: none;
}

/* ─── Registration Button ─── */
.registration-btn {
    background: linear-gradient(
        135deg,
        var(--primary-color) 0%,
        var(--secondary-color) 100%
    );
    color: #fff;
    padding: 0.75rem 1.5rem;
    border-radius: 10px;
    text-decoration: none;
    font-weight: 600;
    font-size: 0.95rem;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.3);
    border: none;
    cursor: pointer;
    position: relative;
    overflow: hidden;
    white-space: nowrap;
    flex-shrink: 0;
}

.registration-btn::before {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.2);
    transform: translate(-50%, -50%);
    transition:
        width 0.6s,
        height 0.6s;
}
.registration-btn:hover::before {
    width: 300px;
    height: 300px;
}
.registration-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(99, 102, 241, 0.5);
}
.registration-btn:active {
    transform: translateY(0);
}

/* ─── Hamburger (hidden on desktop) ─── */
.hamburger {
    display: none; /* shown only on mobile via media query */
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    width: 40px;
    height: 40px;
    padding: 6px;
    z-index: 1001;
    flex-shrink: 0;
}

.hamburger-line {
    display: block;
    width: 24px;
    height: 2.5px;
    background: #fff;
    border-radius: 2px;
    transition:
        transform 0.35s ease,
        opacity 0.35s ease;
}

/* animated "X" state */
.hamburger.active .hamburger-line:nth-child(1) {
    transform: translateY(7.5px) rotate(45deg);
}
.hamburger.active .hamburger-line:nth-child(2) {
    opacity: 0;
}
.hamburger.active .hamburger-line:nth-child(3) {
    transform: translateY(-7.5px) rotate(-45deg);
}

/* ─── Dropdown Menu (desktop hover) ─── */
.dropdown {
    position: relative;
}
.dropdown-toggle {
    cursor: pointer;
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    background: #fff;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    min-width: 220px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.15);
    display: flex;
    flex-direction: column;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition:
        opacity 0.3s ease,
        visibility 0.3s ease,
        transform 0.3s ease;
    z-index: 1000;
    margin-top: 0.5rem;
    backdrop-filter: blur(10px);
}

.dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-menu a {
    padding: 0.75rem 1rem;
    text-decoration: none;
    color: var(--text-dark);
    border-bottom: 1px solid var(--border-color);
    transition: all 0.3s ease;
    font-size: 0.92rem;
}
.dropdown-menu a:last-child {
    border-bottom: none;
}
.dropdown-menu a:hover {
    background: linear-gradient(
        135deg,
        rgba(99, 102, 241, 0.15),
        rgba(139, 92, 246, 0.15)
    );
    color: var(--primary-color);
    font-weight: 600;
    padding-left: 1.25rem;
    transform: translateX(5px);
}

/* ============================================================
   MAIN & PARTICLES
   ============================================================ */
main {
    max-width: 1400px;
    margin: auto;
    position: relative;
}

.particles {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
    pointer-events: none;
}

.particle {
    position: absolute;
    background: white;
    border-radius: 50%;
    animation: twinkle var(--duration) infinite;
    opacity: 0;
}

@keyframes twinkle {
    0%,
    100% {
        opacity: 0;
    }
    50% {
        opacity: var(--opacity);
    }
}

/* ============================================================
   BUTTONS
   ============================================================ */
.btn-black-white,
.btn-primary,
.btn-secondary,
.btn-large {
    background: linear-gradient(
        135deg,
        var(--primary-color) 0%,
        var(--secondary-color) 100%
    );
    color: #fff;
    border: none;
    padding: 0.9rem 2rem;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    border-radius: 12px;
    text-decoration: none;
    font-weight: 600;
    box-shadow: 0 4px 20px rgba(99, 102, 241, 0.4);
    position: relative;
    overflow: hidden;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-family: "Inter", sans-serif;
}

.btn-secondary {
    background: transparent;
    border: 2px solid rgba(255, 255, 255, 0.3);
    backdrop-filter: blur(10px);
}
.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.5);
}

.btn-black-white::before,
.btn-primary::before,
.btn-large::before {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.3);
    transform: translate(-50%, -50%);
    transition:
        width 0.6s,
        height 0.6s;
}
.btn-black-white:hover::before,
.btn-primary:hover::before,
.btn-large:hover::before {
    width: 400px;
    height: 400px;
}

.btn-black-white:hover,
.btn-primary:hover,
.btn-large:hover {
    transform: translateY(-3px);
    box-shadow: 0 12px 35px rgba(99, 102, 241, 0.5);
}
.btn-black-white:active,
.btn-primary:active,
.btn-large:active {
    transform: translateY(-1px);
}

.btn-large {
    padding: 1.2rem 2.5rem;
    font-size: 1.1rem;
    border-radius: 15px;
}

/* ============================================================
   FOOTER
   ============================================================ */
footer {
    background: rgba(15, 23, 42, 0.95);
    backdrop-filter: blur(20px);
    color: white;
    padding: 3rem 2rem 2rem;
    text-align: center;
    margin-top: 0;
    border-top: 1px solid rgba(99, 102, 241, 0.3);
    animation: slideUp 0.5s ease-out 0.3s both;
    position: relative;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
}

.footer-section h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    background: linear-gradient(
        135deg,
        var(--primary-color),
        var(--secondary-color)
    );
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.social-links {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-top: 1rem;
}

.social-links a {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.1);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    transition: all 0.3s ease;
    text-decoration: none;
}
.social-links a:hover {
    background: linear-gradient(
        135deg,
        var(--primary-color),
        var(--secondary-color)
    );
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(99, 102, 241, 0.4);
}

.footer-divider {
    height: 1px;
    background: linear-gradient(
        90deg,
        transparent,
        rgba(255, 255, 255, 0.3),
        transparent
    );
    margin: 2rem 0 1.5rem;
}

.footer-credit {
    font-size: 0.9rem;
    opacity: 0.8;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ============================================================
   HOME – HERO
   ============================================================ */
.home-main {
    background: transparent;
    position: relative;
    min-height: 100vh;
}
.home-main::before {
    display: none;
}

.hero {
    text-align: center;
    padding: 8rem 2rem 6rem;
    background: transparent;
    margin: 0;
    position: relative;
    overflow: hidden;
    min-height: 90vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 0;
    overflow: hidden;
}

/* Animated blobs */
.planet {
    position: absolute;
    border-radius: 50%;
    animation: orbit 30s linear infinite;
}
.planet-1 {
    width: 300px;
    height: 300px;
    background: radial-gradient(circle at 30% 30%, #a78bfa, #7c3aed);
    top: 10%;
    right: 10%;
    opacity: 0.3;
    filter: blur(40px);
    animation-duration: 40s;
}
.planet-2 {
    width: 200px;
    height: 200px;
    background: radial-gradient(circle at 30% 30%, #f472b6, #ec4899);
    bottom: 20%;
    left: 5%;
    opacity: 0.25;
    filter: blur(35px);
    animation-duration: 35s;
    animation-direction: reverse;
}
.planet-3 {
    width: 150px;
    height: 150px;
    background: radial-gradient(circle at 30% 30%, #60a5fa, #3b82f6);
    top: 50%;
    left: 50%;
    opacity: 0.2;
    filter: blur(30px);
    animation-duration: 25s;
}

@keyframes orbit {
    0% {
        transform: translate(0, 0) rotate(0deg);
    }
    25% {
        transform: translate(50px, -50px) rotate(90deg);
    }
    50% {
        transform: translate(0, -100px) rotate(180deg);
    }
    75% {
        transform: translate(-50px, -50px) rotate(270deg);
    }
    100% {
        transform: translate(0, 0) rotate(360deg);
    }
}

.stars {
    position: absolute;
    width: 100%;
    height: 100%;
    background-image:
        radial-gradient(2px 2px at 20px 30px, white, transparent),
        radial-gradient(2px 2px at 60px 70px, white, transparent),
        radial-gradient(1px 1px at 50px 50px, white, transparent),
        radial-gradient(1px 1px at 130px 80px, white, transparent),
        radial-gradient(2px 2px at 90px 10px, white, transparent);
    background-size: 200px 200px;
    animation: twinkleStars 5s ease-in-out infinite;
    opacity: 0.4;
}

@keyframes twinkleStars {
    0%,
    100% {
        opacity: 0.4;
    }
    50% {
        opacity: 0.7;
    }
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 1000px;
}

.hero-title {
    margin-bottom: 1.5rem;
}

.gradient-text {
    font-size: 2.5rem;
    font-weight: 600;
    background: linear-gradient(135deg, #a5b4fc, #c4b5fd);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    display: block;
    animation: fadeInUp 0.8s ease-out 0.1s both;
}

.main-title {
    font-size: 5rem;
    font-weight: 900;
    background: linear-gradient(135deg, #ffffff, #e0e7ff);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    display: block;
    letter-spacing: -2px;
    animation: fadeInUp 0.8s ease-out 0.2s both;
    text-shadow: 0 0 80px rgba(165, 180, 252, 0.5);
    font-family: "Space Grotesk", sans-serif;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero .subtitle {
    font-size: 1.8rem;
    font-weight: 600;
    margin-bottom: 2.5rem;
    color: #cbd5e1;
    animation: fadeInUp 0.8s ease-out 0.3s both;
    position: relative;
    z-index: 2;
}

.conference-date {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    background: linear-gradient(135deg, #ff6b35, #f7931e);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: fadeInUp 0.8s ease-out 0.25s both;
    position: relative;
    z-index: 2;
    letter-spacing: 0.5px;
}

.hosted-by {
    font-size: 1.15rem;
    font-weight: 500;
    margin-bottom: 1.5rem;
    color: #a5b4fc;
    animation: fadeInUp 0.8s ease-out 0.4s both;
    position: relative;
    z-index: 2;
    letter-spacing: 0.3px;
}

.cta-buttons {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
    margin-top: 2.5rem;
    flex-wrap: wrap;
    animation: fadeInUp 0.8s ease-out 0.7s both;
}

/* ============================================================
   CONTENT AREA
   ============================================================ */
.content {
    padding: 4rem 2rem;
    background: transparent;
    max-width: 1400px;
    margin: auto;
    position: relative;
    z-index: 1;
}

/* ─── Section Headers ─── */
.section-header {
    text-align: center;
    margin-bottom: 3rem;
}

.section-tag {
    display: inline-block;
    background: rgba(99, 102, 241, 0.2);
    color: var(--nebula-pink);
    padding: 0.5rem 1.5rem;
    border-radius: 50px;
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 1rem;
    border: 1px solid rgba(99, 102, 241, 0.3);
}

.section-header h2 {
    font-size: 2.5rem;
    color: white;
    font-weight: 800;
    margin: 0;
    font-family: "Space Grotesk", sans-serif;
}

/* ─── About ─── */
.about-section {
    margin-bottom: 5rem;
}

.about-content {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: 3rem;
    align-items: center;
}

.about-text {
    color: #cbd5e1;
}

.intro-text {
    font-size: 1.2rem;
    line-height: 1.8;
    margin-bottom: 1.5rem;
    color: #e2e8f0 !important;
}

.highlight-text {
    color: var(--nebula-pink);
    font-weight: 700;
}

.about-text p {
    font-size: 1.05rem;
    line-height: 1.8;
    margin-bottom: 1.5rem;
    color: #cbd5e1;
}

.about-image {
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(20px);
    border-radius: 20px;
    padding: 3rem;
    border: 1px solid rgba(255, 255, 255, 0.1);
    transition: all 0.4s ease;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
}

.about-image img {
    width: 100%;
    height: auto;
    max-width: 100%;
    object-fit: cover;
    border-radius: 12px;
    transition: transform 0.4s ease;
}

.about-image:hover {
    transform: scale(1.02);
    box-shadow: 0 20px 40px rgba(99, 102, 241, 0.3);
}
.about-image:hover img {
    transform: scale(1.05);
}

/* ─── Important Dates ─── */
.important-dates-section {
    margin-bottom: 5rem;
}

.dates-table-wrapper {
    overflow-x: auto;
}

.dates-table {
    width: 100%;
    border-collapse: collapse;
    background: rgba(30, 27, 75, 0.6);
    backdrop-filter: blur(20px);
    border: 1px solid rgba(99, 102, 241, 0.3);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 8px 32px rgba(99, 102, 241, 0.1);
}

.dates-table thead {
    background: linear-gradient(
        135deg,
        rgba(99, 102, 241, 0.2),
        rgba(139, 92, 246, 0.2)
    );
    border-bottom: 2px solid rgba(99, 102, 241, 0.3);
}

.dates-table thead th {
    padding: 1.5rem 2rem;
    text-align: left;
    font-size: 1.1rem;
    font-weight: 700;
    color: #e2e8f0;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.dates-table tbody tr {
    border-bottom: 1px solid rgba(99, 102, 241, 0.2);
    transition: all 0.3s ease;
}
.dates-table tbody tr:last-child {
    border-bottom: none;
}
.dates-table tbody tr:hover {
    background: rgba(99, 102, 241, 0.1);
}

.dates-table tbody td {
    padding: 1.5rem 2rem;
    font-size: 1rem;
    color: #cbd5e1;
}

.event-name {
    font-weight: 600;
    color: #e2e8f0;
    min-width: 250px;
}

.event-date {
    font-weight: 700;
    font-size: 1.1rem;
    font-family: "Space Grotesk", sans-serif;
}

.deadline-row .event-date {
    color: #fca5a5;
}
.registration-row .event-date {
    color: #fbbf24;
}
.event-row .event-date {
    color: #86efac;
}

/* ─── Highlights ─── */
.highlights-section {
    margin-bottom: 5rem;
}

.highlights-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.highlight-card {
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(20px);
    padding: 2rem;
    border-radius: 15px;
    border: 1px solid rgba(255, 255, 255, 0.1);
    position: relative;
    overflow: hidden;
    transition: all 0.4s ease;
}

.highlight-card::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(
        90deg,
        var(--primary-color),
        var(--secondary-color)
    );
    transform: scaleX(0);
    transition: transform 0.4s ease;
}
.highlight-card:hover::before {
    transform: scaleX(1);
}
.highlight-card:hover {
    transform: translateY(-5px);
    background: rgba(255, 255, 255, 0.08);
    box-shadow: 0 15px 30px rgba(99, 102, 241, 0.3);
}

.highlight-number {
    font-size: 3rem;
    font-weight: 900;
    background: linear-gradient(
        135deg,
        var(--primary-color),
        var(--secondary-color)
    );
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    opacity: 0.3;
    margin-bottom: 1rem;
    font-family: "Space Grotesk", sans-serif;
}

.highlight-card h3 {
    color: white;
    font-size: 1.2rem;
    margin-bottom: 0.8rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.highlight-card h3 i {
    color: var(--nebula-pink);
}

.highlight-card p {
    color: #cbd5e1;
    font-size: 0.95rem;
    line-height: 1.6;
    margin: 0;
}

/* ─── Topics ─── */
.topics-section {
    margin-bottom: 5rem;
}

.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
}

.topic-item {
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(20px);
    padding: 1.5rem;
    border-radius: 12px;
    border: 1px solid rgba(255, 255, 255, 0.1);
    display: flex;
    align-items: center;
    gap: 1rem;
    transition: all 0.3s ease;
    color: white;
    font-weight: 600;
}
.topic-item:hover {
    background: rgba(255, 255, 255, 0.1);
    transform: translateX(10px);
    border-color: rgba(99, 102, 241, 0.4);
    box-shadow: 0 10px 20px rgba(99, 102, 241, 0.2);
}
.topic-item i {
    font-size: 1.5rem;
    color: var(--nebula-pink);
    min-width: 30px;
}

/* ─── CTA ─── */
.cta-section {
    background: linear-gradient(
        135deg,
        rgba(99, 102, 241, 0.2),
        rgba(139, 92, 246, 0.2)
    );
    backdrop-filter: blur(20px);
    padding: 4rem 2rem;
    border-radius: 25px;
    text-align: center;
    border: 1px solid rgba(99, 102, 241, 0.3);
    margin-top: 4rem;
    position: relative;
    overflow: hidden;
}

.cta-section::before {
    content: "";
    position: absolute;
    top: -50%;
    right: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(236, 72, 153, 0.1), transparent);
    animation: rotate 20s linear infinite;
}

@keyframes rotate {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}

.cta-content {
    position: relative;
    z-index: 1;
}

.cta-content h2 {
    font-size: 2.5rem;
    color: white;
    margin-bottom: 1rem;
    font-weight: 800;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
}
.cta-content h2 i {
    color: var(--nebula-pink);
}
.cta-content p {
    font-size: 1.2rem;
    color: #cbd5e1;
    margin-bottom: 2rem;
}

/* ============================================================
   CAROUSEL
   ============================================================ */
.carousel-section {
    width: 100%;
    padding: 2rem 0;
    background: linear-gradient(
        135deg,
        rgba(99, 102, 241, 0.1),
        rgba(139, 92, 246, 0.1)
    );
    display: flex;
    justify-content: center;
    align-items: center;
}

.carousel-container {
    position: relative;
    max-width: 900px;
    width: 90%;
    margin: 0 auto;
    background: white;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
}

.carousel-wrapper {
    position: relative;
    width: 100%;
    padding-bottom: 66.67%;
}

.carousel-slide {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    transition: opacity 0.6s ease-in-out;
}
.carousel-slide.active {
    opacity: 1;
}

.carousel-slide img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.carousel-btn {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background-color: rgba(0, 0, 0, 0.6);
    color: white;
    border: none;
    font-size: 1.5rem;
    padding: 0.8rem 1rem;
    cursor: pointer;
    border-radius: 4px;
    transition: background-color 0.3s ease;
    z-index: 10;
}
.carousel-btn:hover {
    background-color: rgba(0, 0, 0, 0.9);
}
.carousel-btn.prev {
    left: 10px;
}
.carousel-btn.next {
    right: 10px;
}

.carousel-dots {
    position: absolute;
    bottom: 15px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 0.5rem;
    z-index: 10;
}

.dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background-color: rgba(255, 255, 255, 0.6);
    cursor: pointer;
    transition: background-color 0.3s ease;
}
.dot.active {
    background-color: white;
}
.dot:hover {
    background-color: rgba(255, 255, 255, 0.9);
}

/* ================= DESKTOP DEFAULT ================= */
#navMenu {
    display: flex;
    gap: 2rem;
}

.navlinks {
    display: flex;
    gap: 2rem;
}

.hamburger {
    display: none;
}

/* ============================================================
   MOBILE RESPONSIVE  (≤ 768 px)
   ============================================================ */
@media (max-width: 768px) {
    /* ─── Header padding ─── */
    header {
        padding: 0.85rem 0;
    }

    .navbar {
        padding: 0 1rem;
    }

    /* ─── Logo group – shrink logos ─── */
    .navbar-logo-group {
        gap: 0.75rem;
        margin-right: 0;
    }
    .iit-logo {
        height: 32px;
    }
    .logo {
        height: 42px;
    }

    /* ─── Show hamburger ─── */
    .hamburger {
        display: flex;
    }

    /* ─── Nav menu – full-width slide-down panel ─── */
    .nav-menu {
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background: rgba(15, 23, 42, 0.97);
        backdrop-filter: blur(24px);
        border-top: 1px solid rgba(99, 102, 241, 0.25);
        flex-direction: column;
        align-items: stretch;
        padding: 0;
        /* collapsed state */
        max-height: 0;
        overflow: hidden;
        opacity: 0;
        transition:
            max-height 0.45s cubic-bezier(0.4, 0, 0.2, 1),
            opacity 0.35s ease,
            padding 0.35s ease;
    }

    .nav-menu.open {
        max-height: 600px; /* tall enough for all links */
        opacity: 1;
        padding: 1rem 0 1.25rem;
    }

    /* ─── Nav links – stacked vertical list ─── */
    .navlinks {
        flex-direction: column;
        gap: 0;
        padding: 0 1.25rem;
    }

    .navlinks > li {
        border-bottom: 1px solid rgba(255, 255, 255, 0.07);
    }
    .navlinks > li:last-child {
        border-bottom: none;
    }

    .navlinks > li > a {
        display: flex;
        justify-content: space-between;
        width: 100%;
        padding: 0.85rem 0;
        font-size: 1rem;
        color: #e2e8f0;
    }
    .navlinks > li > a::after {
        display: none;
    } /* remove desktop underline */
    .navlinks > li > a:hover {
        transform: none;
        color: #fff;
    }

    /* show chevrons on mobile */
    .dropdown-arrow {
        display: inline-block;
        font-size: 0.7rem;
        color: #a5b4fc;
        transition: transform 0.3s ease;
    }

    .dropdown.open .dropdown-arrow {
        transform: rotate(180deg);
    }

    /* ─── Dropdown menu – accordion style ─── */
    .dropdown-menu {
        position: static;
        opacity: 1;
        visibility: hidden;
        transform: none;
        background: rgba(30, 27, 75, 0.7);
        border: none;
        border-radius: 10px;
        margin: 0.4rem 0 0.6rem;
        padding: 0.3rem 0;
        max-height: 0;
        overflow: hidden;
        transition:
            max-height 0.35s cubic-bezier(0.4, 0, 0.2, 1),
            visibility 0.35s ease;
        box-shadow: none;
    }

    .dropdown.open .dropdown-menu {
        max-height: 300px;
        visibility: visible;
    }

    /* override desktop hover rule on mobile */
    .dropdown:hover .dropdown-menu {
        opacity: 1;
        visibility: hidden;
        transform: none;
    }
    .dropdown.open .dropdown-menu {
        visibility: visible;
    }

    .dropdown-menu a {
        padding: 0.7rem 1rem;
        color: #cbd5e1;
        font-size: 0.92rem;
        border-bottom: 1px solid rgba(255, 255, 255, 0.06);
    }
    .dropdown-menu a:hover {
        background: rgba(99, 102, 241, 0.15);
        color: #fff;
        padding-left: 1.2rem;
        transform: none;
    }

    /* ─── Registration button inside panel ─── */
    .registration-btn {
        display: block;
        width: calc(100% - 2.5rem);
        margin: 0.75rem 1.25rem 0;
        text-align: center;
        padding: 0.8rem 1rem;
        font-size: 0.95rem;
    }

    /* ============================================================
     HERO – mobile
     ============================================================ */
    .hero {
        padding: 5rem 1.25rem 3.5rem;
        min-height: auto;
    }

    .gradient-text {
        font-size: 1.4rem;
    }
    .main-title {
        font-size: 2.8rem;
        letter-spacing: -1px;
    }

    .hero .subtitle {
        font-size: 1.1rem;
        margin-bottom: 1.25rem;
        line-height: 1.5;
    }

    .conference-date {
        font-size: 1.15rem;
        margin-bottom: 0.8rem;
    }

    .hosted-by {
        font-size: 0.88rem;
        line-height: 1.55;
        margin-bottom: 1rem;
        padding: 0 0.25rem;
    }

    .cta-buttons {
        flex-direction: column;
        align-items: center;
        gap: 0.85rem;
        margin-top: 1.75rem;
    }

    .btn-primary,
    .btn-secondary {
        width: 100%;
        max-width: 280px;
        justify-content: center;
        padding: 0.8rem 1.5rem;
        font-size: 0.95rem;
    }

    /* ============================================================
     CAROUSEL – mobile
     ============================================================ */
    .carousel-section {
        padding: 1rem 0;
    }
    .carousel-container {
        width: 95%;
        border-radius: 10px;
    }

    .carousel-btn {
        font-size: 1.1rem;
        padding: 0.55rem 0.7rem;
    }

    /* ============================================================
     CONTENT – mobile
     ============================================================ */
    .content {
        padding: 2.5rem 1.25rem;
    }

    .section-header {
        margin-bottom: 1.75rem;
    }
    .section-tag {
        font-size: 0.78rem;
        padding: 0.4rem 1rem;
    }
    .section-header h2 {
        font-size: 1.7rem;
    }

    /* ─── About ─── */
    .about-section {
        margin-bottom: 3rem;
    }
    .about-content {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    .intro-text {
        font-size: 1rem;
        line-height: 1.7;
    }
    .about-text p {
        font-size: 0.93rem;
    }
    .about-image {
        padding: 1rem;
    }

    /* ─── Important Dates ─── */
    .important-dates-section {
        margin-bottom: 3rem;
    }

    .dates-table thead th,
    .dates-table tbody td {
        padding: 0.85rem 0.75rem;
        font-size: 0.88rem;
    }
    .event-name {
        min-width: unset;
        font-size: 0.88rem;
    }
    .event-date {
        font-size: 0.9rem;
    }

    /* ─── Highlights ─── */
    .highlights-section {
        margin-bottom: 3rem;
    }
    .highlights-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    .highlight-card {
        padding: 1.4rem;
    }
    .highlight-number {
        font-size: 2.2rem;
        margin-bottom: 0.5rem;
    }
    .highlight-card h3 {
        font-size: 1.05rem;
    }
    .highlight-card p {
        font-size: 0.88rem;
    }

    /* ─── Topics ─── */
    .topics-section {
        margin-bottom: 3rem;
    }
    .topics-grid {
        grid-template-columns: 1fr;
        gap: 0.85rem;
    }
    .topic-item {
        padding: 1rem 1.1rem;
        font-size: 0.9rem;
    }
    .topic-item i {
        font-size: 1.2rem;
    }
    .topic-item:hover {
        transform: translateX(6px);
    }

    /* ─── CTA ─── */
    .cta-section {
        padding: 2.5rem 1.25rem;
        border-radius: 18px;
        margin-top: 2.5rem;
    }
    .cta-content h2 {
        font-size: 1.6rem;
        flex-wrap: wrap;
        gap: 0.5rem;
    }
    .cta-content p {
        font-size: 1rem;
        margin-bottom: 1.5rem;
    }
    .btn-large {
        padding: 0.9rem 2rem;
        font-size: 1rem;
        width: 100%;
        max-width: 280px;
        justify-content: center;
    }

    /* ─── Footer ─── */
    footer {
        padding: 2rem 1.25rem 1.5rem;
    }
    .footer-section h3 {
        font-size: 1.2rem;
    }
}

/* ============================================================
   EXTRA-SMALL  (≤ 360 px)  – fine-tune for very small screens
   ============================================================ */
@media (max-width: 360px) {
    .iit-logo {
        height: 26px;
    }
    .logo {
        height: 34px;
    }

    .main-title {
        font-size: 2.2rem;
    }
    .gradient-text {
        font-size: 1.2rem;
    }
    .hero .subtitle {
        font-size: 0.97rem;
    }
    .conference-date {
        font-size: 1rem;
    }
    .hosted-by {
        font-size: 0.8rem;
    }

    .section-header h2 {
        font-size: 1.45rem;
    }
    .intro-text {
        font-size: 0.9rem;
    }
}